static int stream_seek_frame(mpg123_handle *fr, off_t newframe)
{
debug2("seek_frame to %"OFF_P" (from %"OFF_P")", (off_p)newframe, (off_p)fr->num);
/* Seekable streams can go backwards and jump forwards.
Non-seekable streams still can go forward, just not jump. */
if((fr->rdat.flags & READER_SEEKABLE) || (newframe >= fr->num))
{
off_t preframe; /* a leading frame we jump to */
off_t seek_to; /* the byte offset we want to reach */
off_t to_skip; /* bytes to skip to get there (can be negative) */
/*
now seek to nearest leading index position and read from there until newframe is reached.
We use skip_bytes, which handles seekable and non-seekable streams
(the latter only for positive offset, which we ensured before entering here).
*/
seek_to = frame_index_find(fr, newframe, &preframe);
/* No need to seek to index position if we are closer already.
But I am picky about fr->num == newframe, play safe by reading the frame again.
If you think that's stupid, don't call a seek to the current frame. */
if(fr->num >= newframe || fr->num < preframe)
{
to_skip = seek_to - fr->rd->tell(fr);
if(fr->rd->skip_bytes(fr, to_skip) != seek_to)
return READER_ERROR;
debug2("going to %lu; just got %lu", (long unsigned)newframe, (long unsigned)preframe);
fr->num = preframe-1; /* Watch out! I am going to read preframe... fr->num should indicate the frame before! */
}
while(fr->num < newframe)
{
/* try to be non-fatal now... frameNum only gets advanced on success anyway */
if(!read_frame(fr)) break;
}
/* Now the wanted frame should be ready for decoding. */
debug1("arrived at %lu", (long unsigned)fr->num);
return MPG123_OK;
}
else
{
fr->err = MPG123_NO_SEEK;
return READER_ERROR; /* invalid, no seek happened */
}
}
static int stream_seek_frame( mpg123_handle_t *fr, mpg_off_t newframe )
{
// seekable streams can go backwards and jump forwards.
// non-seekable streams still can go forward, just not jump.
if(( fr->rdat.flags & READER_SEEKABLE ) || ( newframe >= fr->num ))
{
mpg_off_t preframe; // a leading frame we jump to
mpg_off_t seek_to; // the byte offset we want to reach
mpg_off_t to_skip; // bytes to skip to get there (can be negative)
// now seek to nearest leading index position and read from there until newframe is reached.
// we use skip_bytes, which handles seekable and non-seekable streams
// (the latter only for positive offset, which we ensured before entering here).
seek_to = frame_index_find( fr, newframe, &preframe );
// no need to seek to index position if we are closer already.
// but I am picky about fr->num == newframe, play safe by reading the frame again.
// if you think that's stupid, don't call a seek to the current frame.
if( fr->num >= newframe || fr->num < preframe )
{
to_skip = seek_to - fr->rd->tell( fr );
if( fr->rd->skip_bytes( fr, to_skip ) != seek_to )
return MPG123_ERR;
fr->num = preframe - 1; // watch out! I am going to read preframe... fr->num should indicate the frame before!
}
while( fr->num < newframe )
{
// try to be non-fatal now... frameNum only gets advanced on success anyway
if( !read_frame( fr )) break;
}
// now the wanted frame should be ready for decoding.
return MPG123_OK;
}
else
{
fr->err = MPG123_NO_SEEK;
return MPG123_ERR; // invalid, no seek happened
}
}
